Hypertriton lifetime

Over the last decade, conflicting values of the hypertriton ${}_{\Lambda}^3\mathrm{H}$ lifetime $\tau({}_{\Lambda}^3\mathrm{H})$ were extracted from relativistic heavy-ion (RHI) collision experiments, ranging from values compatible with the free-$\Lambda$ lifetime $\tau_\Lambda$-as expected naively for a very weakly bound $\Lambda$ in ${}_{\Lambda}^3\mathrm{H}$-to lifetimes as short as $\tau({}_{\Lambda}^3\mathrm{H}) \approx (0.4-0.7)\,\tau_\Lambda$. In a recent work [1] we studied this ${}_{\Lambda}^3\mathrm{H}$ lifetime puzzle theoretically using realistic three-body ${}_{\Lambda}^3\mathrm{H}$ and ${}^3\mathrm{He}$ wave functions computed within the ab initio no-core shell model approach with interactions derived from chiral effective field theory. In particular, $\tau({}_{\Lambda}^3\mathrm{H})$ was found to be strongly correlated with the $\Lambda$ separation energy $B_\Lambda$ in ${}_{\Lambda}^3\mathrm{H}$, the value of which is rather poorly known experimentally and, in addition, is known to suffer from sizable theoretical uncertainties inherent in the employed nuclear and hypernuclear interaction models. In the present work we find that these uncertainties propagate into $\tau({}_{\Lambda}^3\mathrm{H})$, and thus limit considerably the theoretical precision of its computed value. Although none of the conflicting RHI measured $\tau({}_{\Lambda}^3\mathrm{H})$ values can be excluded, but rather can be attributed to a poor knowledge of $B_\Lambda$, we note the good agreement between the lifetime value $\tau({}_{\Lambda}^3\mathrm{H})=238(27)$ ps computed at the lowest value $B_\Lambda=66$ keV reached by us and the very recent ALICE measured lifetime value $\tau^{\mathrm{ALICE}}({}_{\Lambda}^3\mathrm{H})=253(11)(6)$ ps associated with the ALICE measured $B_\Lambda$ value $B^{\mathrm{ALICE}}_\Lambda=102(63)(67)$ keV [2].